Why Do Some Truck Tires Don't Touch The Ground?
Why Do Some Truck Tires Don't Touch The Ground?
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Ever wondered why some trucks seem to have wheels in mid-air? Curious minds, this one's for you! In our latest video, we're diving deep into the world of truck axles, demystifying why certain trucks sport floating tires and how it impacts their performance.
Hit the play button, like, share, and subscribe for more intriguing insights into the world of trucks! Stay tuned and keep on trucking! 🚚✨
▬▬▬ The video ▬▬▬
00:00 Start
00:27
Explanation of Axles:
02:00 6 Reasons to choose lift axle
04:52
How liftable axles work
05:40 Conclusion
▬▬▬ End ▬▬▬
Hope you liked this video with Why Do Some Truck Tires Don't Touch The Ground?
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I’ll be honest, it was hard to listen past 34s where you said the axles support the weight of the vehicle. Was this an uncommon mistake by this channel?
Excellent video, knowledge dense!
😂 you're explanation is mostly incorrect but hey I only drive a tri-ax
Went straight to conclusion.
Decode the cartesian plane. Oh, it's not a cryptographic code, but a tool and concept? So it can only be explained? Learn something everyday.
TLDR: The axel can be raised or lowered to distribute the weight of the truck for various reasons including traction, fuel efficiency, reduced costs and maintenance.
Main reason weight distribution to stay legal on axle weights. Per dot regulation you can only have so much weight on an axle. Having a lift axle allows more weight to be carried legally
Thanks for that. No need to watch the video now. I’m out! ✌️
bro really tried to spend 6 minutes to explain 1 sentence
@@jc_yadiggand he repeated ut 25 times💀
also road wear which is also related to legal restrictions on road use.
I once got a ride from a truck driver and I asked him this exact question and he gave me this same explanation in details. He also explained me how the gear box of a truck works, which is quite different from a car. That was a very informative trip.
Did you have to "pay him back" for the ride? 😮
@@poopyanalbumhole good thing it was a joke!
@@JonSanders Oh no, that was free. I may be broke but I'm no prostitute.
@@Dargonhuman I've just seen movies and have heard crazy enough stories to never try such a thing. I'm glad you're trusting and nothing happened, though ❤️
@@JonSanders lots of stuff happened. It was all consensual though.
Oh! I knew it had something to do with how much weight the truck was hauling. But I just learned that the raised wheels don't just plunk themselves down on the road when the weight is "enough". I appreciate learning things like this. I was also not aware of the other reasons it can be advantageous to raise or lower the 'extra' axles.
Same!😅
If you put enough weight on the truck all the axles will touch the road 😅
gotta love KZhead!
wtf no? It have nothing to do with weight, the LORRY is hauling. Its the spare tire.
I always thought the ones up on the frame like that were spares. . .
The largest reason in the US, mentioned in the video, is for weight distribution on construction vehicles, like cement trucks or dump trucks, or heavy haul trucks. Another thing not mentioned in the video is that lift axles are rarely, if ever, powered and are only there to provide extra load-bearing capacity.
So how do they lower when needed and raise when you don't need them? Does the vehicles frame rails actually flex a bit under the load and the flexing and sagging of the frame is enough to bring the wheels to the point where they touch the road?
At 4:52 you can see two sets of air bags. The smaller ones lower and on their side will inflate and push the axle upward, the larger ones deflating at the same time. The large ones are the main suspension bags, and will inflate to push the axle down to the road and bear weight while the smaller ones deflate.
@coolsnake1134 They are on air bags, air up and air down. You just flip a switch in the cab. It's pretty easy. Most of my dump trucks have 4 lift axles, leave them up empty or put one or all down when loaded. Because the lovely state of Ohio will bust you if not.
@@gumballer133 Did you know that it is illegal to use them in Canada?
@johnarnold893 Really? They have to be down permanently?
This could have been a 60 sec video
60 secs is not long enough for proper procrastination
Here in the UK nearly all tractor units are the 6×2 configuration ie 6 wheels 2 wheels powered with a lift axle on the middle, the lift axle will only lift if the weight on the drive axle is below the maximum axle weight, we operate double deck trailers and you have to run with the lift axle down at all times as lifting the axle could cause the suspension plates or the rear bumper to ground, running with the axle raised increases the height so the trailers could be above 16"6" which is the legal height limit in the UK and potentially cause a bridge strike but this would be rare as most bridges are about 17" on main trunk roads
The automatic control is important. Without it, drivers would drive with high load and the axle lifted, causing excessive load on the non-lifting axle. This is the reason that the use of lift axles is restricted in western Canadian provinces - the regulators don't trust drivers to avoid overloading by incompetent or reckless operation.
Only 17”?! Holy moly that’s short
Obviously the heights were supposed to be 16'7" and 17',@@fredfrederickson
@@brianb-p6586 So they built them all nearly 16 feet short of the height they’re supposed to be? That’s even worse!
@@brianb-p6586 If you think you have to force people to do what they should you've already failed as a manager/regulator. The entire US is literally proof that you don't.
Being able to lift the boggie axle and apply as much pressure on the powered axle is definitely a must, up here in Sweden, during the winter. However, once you get on the motorway, you usually have it lowered, so that the truck isn't so wobbly to keep going straight.
Glad you say this because the video did not make it clear that the way to increase traction is to RAISE the axle.
Same in Norway. Usually the lorries can't lift the boggie if the weight is too high, but up here in the north, we can. Lifting a boggie axle when fully loaded, can give you 20+ tons pressure on the driveaxle, and therefore gives you ALOT more grip on slippery surface. Like Skelterbane69 says, once we're on the bare road, the axles goes back down to keep the lorry more stable :)
In America most of the time those are automatic. Thats why i dont like them. 2 drive axels are much better the a drive and a lift axel.
@@knightwing4 Our backup truck is a DAF and it's automatic like that too and I hate it. Absolutely worthless in the winter. Wish we had a truck with tandem axles, but it's unnecessary for what we deliver anyway.
@@knightwing4 In what way is fixed tandem drive better than a lift axle? On a tipperlorry, it's understandable. But for 99% of the lorries out on european roads, a boggie lift axle is the way to go. Less wear on the tires, easier to menouver around narrow streets.
I always thought they were required by law to carry a certain number of spare tires. This makes so much more sense. Thanks
Yes they are not spares they do have a purpose. As a trucker I giggled at this comment no hate to you but I wanted to comment for fun 😂
@@SuperBobblehead77 truckers being assholes as always...
@@DutchVanDerLindo Spare Tires he said 🤣🤣
@@SuperBobblehead77 it was a joke stop crying
@@DutchVanDerLindo i thought they are spears too at first, but then i realized how tf would a person be able to handle suck a big and heavy wheel and also jacking up a loaded truck
Back in the old days, pre July 1979, the lift axles were known as Tax Axles, due to the Road Maintenance (Contributive) Tax that was applied in all jurisdictions. They were set up on spring suspensions with a single air bag which was inflated to raise the tax axle. This was generally the rear axle of a tandem group on a rigid, or appropriate axles on a tandem or tri-axle.
“Have you ever driven a truck …” -No
Front lift axles (ahead of drive axles) are often called "Pusher axles" as well. This is because your driveline "pushes" the axle along, rather than "tagging" along the rear. Some trucks also have "steerable" pusher/tag axles. They lock out when retracted.
So cool little bit of side info. Since these wheels are raised and lowered with airbags, most trucks allow you to adjust the pressure in the airbags to maintain proper ground pressure for weight distribution and traction. Too much pressure and you can actually put too much weight on these tires leading to excessive wear and even blowouts and you can even make it to where the drive wheels don’t have enough traction. While too little pressure can effectively mean they aren’t even doing anything. Also a fun little side story, I was doing first time inspection on a truck we bought that had a set of these wheels. I found out the pressure regulator was actually broken for the airbags and when I went to drop the wheels the airbags were so over pressure that you actually couldn’t drive the truck while it was empty because it completely lifted the drive axel about an inch off the ground. Had to basically rebuild the system for the drop wheels because of this
That's literally fake news. I won't say 100% of all trucks, but almost every single truck is equipped with a dump valve. Not a pressure regulator.. we can't just adjust pressures on the fly. Trucks have ride height adjusters though, but they're completely independent from the drivers seat. It's just a lever that moves up and down with the weight of the load that adds or subtracts pressure from the bags to maintain proper height. Has nothing to do with tire ground pressure, or anything else. Strictly a way to maintain the same height regardless of load.
@@sergeantspeed5941 Yeah he thinks that truck axles still use spring and only the tag axles have air bags. Also this garbage video thinks that they actually provide power for some reason because "2?" trucks do.
Sooooo, no. The axles that lift up when not needed have springs to lift them up. When the driver needs them their air bags are tied into the entire truck airbag suspension system to make sure the bullshit you are saying can never happen. And to be clear, The amount of engineering, and cost per truck, it would take to make the tag axles an entire independent system would make it more difficult to use is an order of magnitude more than just tying it into all the other airbags on the drive axles. You obviously have no idea how trucks actually work. You're an idiot.
Actually the real reason for lift axles is toll tax. You pay per axle/wheel on the road. Trailers also have lift axles. When not loaded the axles are lifted to save costs ie, tax. They also have another benefit in that they reduce rolling resistance and save fuel.
I was wondering about the axel payments billboard as I pass through the tollway. It listed as 2 axel payment (regular vehicles) a certain amount and then 3 axel+ payment.
that is dumb. I think it is not like it works you should pay not per axle but per road load using more axles should reduce the amount you pay not increase it because by using fewer you are loading the road more as I know you need ot use more axles not to exceed the allowed axle limits that are often measure by police or automatically
you beat me to it, used to work for a garbage company, we only ever deployed the push axel before hitting the weigh station, then pulled em up as soon as you were off the scale.
The funny thing is that the tax (per axle) is justified by damage done to the road. By running fewer axles, they pay less tax, but the pressure on the road increases accelerating road wear.
@@davidawaters Yes exactly, an idea to tax per axle which is down is beyond stupidity of even average politician, it can be true that they passed such law fo real.
Ive been wondering this for YEARS. Like since 1982! I just never thought to ask or even look it up. Thank you, almightly algorithm!
Thanks for this. I always saw construction trucks with a raised axle which puzzled me. The only explanation in my head, was that it helped as a form of support for when the truck climbed onto mounds at a site to dump its contents.
👍
My imaginative explanation was that if the truck got a flat tyre the driver could drop the lifted axle and raise the one with the flat. I didn't really believe it but it was the best I could think of. Many thanks to the channel creator for solving the mystery for me. Definitely a like 👍👍🌟
I actually asked my dad that about a dump truck (I think I was around 10) and I think he said that it was for when they were going over train tracks so it didn't scrape the underside if it was a little too high of an angle. I'm starting to think he made that up on the spot.
Yeah this is what I thought. I thought they were fixed in place and only there to help drive over uneven surfaces.
BTW you must pay for those axles when using a toll road, whether up or down. I found out a long time age, when towing a truck with lift axles. I had to pay for the wreckers axles and ALL of the trucks axles "including" the lift axle.
I have a drop axle on my freightliner. They are more prevalent in the Pacific Northwest and upper midwest. Nonexistent anywhere else on tractor trailers except for Heavy Haul applications with duals. Used for spreading weight out on drive axle group when you have more than 80,000 gross vehicle weight as the norm. Helps to take weight off drive axles rather than go the the trouble of sliding tandems or fifth wheel. Flip switch and work is done.
Finally a comment with the interesting and necessary information. Also the Pacific Northwest has a ton of cross border deliveries, and the weight limits are all different in Canada. For trucks that have to comply with both sets of regulations, it's very useful to have a couple of different drop axles, including to take weight off the steer axles as well. Steerable drops are not allowed in Canada, so the weight limits end up being higher in the US. The added expense was justified by being able to charge higher than standard rates in order to take a couple of extra units across the border. Fun fact: Idaho has an entire worksheet that a truck driver must complete in order to operate in that state. There are some VERY tight hairpins in some places, and truckers are given the specific roads that they are permitted to drive on based on this worksheet.
@CanCobb wrong I live in Idaho and got my cdl in Idaho as well as drove trucks with lift axles Idaho has no special sheet requirements. Only difference with an 8axle truck over a 5axle truck is making sure your weights as well as length are within legal limits which applies to every truck in every state its called bridge law
Might be referring to truck registration, not company driver responsibility. There are tight roads in Idaho mts I'm sure.
80.000LBS is the maximum weight for all highways in the US. and anything more than that requires tag axles plain and simple.
Wrong. Some states like Washington allow for 105,500 lb. You don't even need a permit you just have to pay extra tonnage on the registration. You would need extra axles to accommodate the weight though. 80,000 lb is for five axle truck.
I drove auto transport trucks for almost 30 years, some of the trucks had a "Tag Axle" some a "Lift Axle". The tag axle was an air suspension axle that when the air was released would still ride on the ground but not carry any weight. The lift axle when no air was applied would lift off the ground.
yes i know the ones you mean very common in new zealand .
I'll watch anything the algorithm gives me at 3am
Thank you for making this video, after many hours playing ETS2 & ATS I've always wondered what use having a liftable axle had, maybe now I'll convert some of my game trucks to have the chassis for them.
Your Welcome :)
Great explanation! With garbage trucks, they put tag axles on the jumbo garbage trucks and lower the tag or tandem axle when the load is too heavy.
I drove a tri-drive for years. Had a few drivers tell me my tag axle was down. Then had to educate them on how tri-drives work.
Drove a coal hauler dump truck. Had a high side dump box and carried 22 tons. Axle in front of the drive axles helped take the load of the front axle. Had to raise them when making a tight turn
I was just thinking about this question and this video showed up. How perfect.
My truck has a steerable pusher axle behind the sleeper. Since I pull a 9 axle RGN, and the Goose-Neck has the pony hydraulic neck on it, the steerable pusher axle allows me to push that extra weight onto the truck tractor. Which allows me to more center load the well deck. But when I don't have the jeep or the booster, the steerable pusher gives me that little extra weight configuration. Keeps me legal. Plus is gives me that little extra control and braking on a downgrade here in the Rockies.
Another benefit of lifting a tag axle is a reduced turning radius. Some Volvo trucks allow you to lift the tag axle at low speed even with a heavy load, and will automatically lower it again when you exceed 30km/h.
Not in the usa
I always subconsciously wondered why. Thanks for this explanation.
I speak about trucks like once a year, last time it was two days ago and exactly about this topic as we crossed a truck that was raising an axle of tires. I was asked about it, answered (by live voice, not even text or voicenote) and now I have this video at the top of my home page...
I felt like i already knew the answer to this, and to an extent i did. I knew the floating axle was for when the truck had heavier loads and figured it was for better weight distribution on the suspension. What i didn't know was that they could be lowered dynamically. I thought they activated when the suspension sunk far enough for the floating wheels to touch the ground. Now i know better, all because i didn't let my hubris skip over this video i thought i already knew the answer to.
I used to work on a rigid refuse truck which had an extra axel like that at the back in front of the main rear one, it lowered automatically once you reached a certain load weight (typically around 22000 KG) though you could also lower it yourself with the onboard computer. I’m not sure if Dennis Eagle makes those types any more. All the later models I used have the single wheel axels behind the main rear axle and they are connected to the steering, thus always down.
I was playing snowtires. My friend bought a truck with this axel we talked about it and this video popped up on my recommendation. LoL
For the longest time I thought the wheels off the ground were the spares for the truck. One day I saw a truck lower the wheels that were previously in the air. Still I thought it was for the purpose of changing the tires since it lifted the other axels up higher off the ground. Now know why. Great informational video.
In Australia with trailers axles raising up is only when empty but if full loaded they’ll lower it down
Nice vid. It was very informative about something I’ve always noticed on the road, but about which I’ve only speculated as to why. It’s nice that this vid helped to validate why I thought larger semis and dump trucks have this feature. Thank you.
i didn't really need this info but youtube insisted and now it'll live in my head forever.
This is honestly a great and very informative video for anyone who is a trucker and also a gamer
Here in South Africa we call our Trucks "Horse and trailers" or the ones with two trailers we call "Super-links" and our are have always two drive axles at the rear(*6x4). Trucks that are 6x2 or 4x2 are considered smaller trucks. The only region or country with bigger trucks than S.Africa is Australia with their Roadtrains
That's just not true on the only place with bigger trucks is Australia
Mines in 🇿🇼 use road trains!
The question I always wanted to figure out but never took the time to look up. Thank you!
The Finnish Sisu trucks are legendary for their axles that can be lifted even when fully loaded and higher than most other brands, enabling you to drive out of that spot where a Scania, MB or Volvo would get stuck.
Thank you for making this video. You have answered the questions I had about this going back 30 years.
You could have googled it
Never really puzzled me. I figured it was for heavier loads and gave the ability to lift and save the tires from wear when not needed. If truck tires are so expensive that they retread them then this must save a lot of money.
Lift axles ahead of the drive axlels are called pusher axlles
Finally the answer to the question I've been thinking about for my whole life
I wasn't looking for this video, but I watched it. Very informative.
Miscellaneous clarifications, corrections, and additions: A "lift axle" is any axle which can be lifted, regardless of position (despite the suggestion that they are only ahead of the rear drive axles). An axle can be both a drive axle and a steer axle - they are different characteristics, not exclusive types. A *tag* axle is any unpowered axle behind the rear drive axles... whether it lifts or not. An unpowered axle ahead of the rear drive axles is often called a *"pusher"* axle. Unpowered axles in the rear (ahead of or behind the drive axles, so pushers or tag) can be passively steered (castered) or actively steered (linked mechanically, hydraulically, or electronically to the main steer axle). Lift axles are used on both trucks (including highway tractors) and trailers. The word is tire "wear", not "ware".
There's also lift axles (usually tag axles) that are powered
@maxi5778 how does a powered lift axle work? Edit: What I mean is how a lift axle can be powered? What keeps it from receiving power while lifted?
Air bags push them up. Reverse air direction and they deflate while full size bags inflate pushing axle to ground.
@@Ronald.Golleherbasically works as a normal tandem drive, when you want tandem drive you lower it and activate the power divider. Disconnect power divider and lift the axle when not needed. I dont know how much of the process is automated (ie. The tandem drive most likely automatically disconnects if you lift the axle) but the principle is more or less the same as for a normal non liftable tandem drive
@@rikardandersson7288 ah that makes sense, assuming either the power is disconnected or the wheels are braced against something so they can't turn.
This has been something that has bugged me for years. I came up with the brilliant solution that an axle was lifted only when making sharp turns, then dropped once on the straight and narrow... I have only seen it them on Dump Trucks, not the Big Rigs. So yeah I feel a bit silly, but also a bit smarter thanks to your explanation. Thank you. 👍👍
You are not wrong. They do raise the extra axles, especially the ones that are on trailers, making turns at intersections. Otherwise, they end up dragging those wheels sideways through the turn which risks damage to tires or even popping a tire of the rim. But, if the vehicle is loaded, you don't want the axle up for too long or the weight might blow one of the tires that's still on the ground. It's a balancing act!
@@Rigel_Chiokis Thank you for that. I feel less silly now. 👍👍
For yard work in places where low speed tight maneuvering is needed a driver might lift the axles to reduce tyre scrub, but it does depend upon the axle configuration of the vehicle.
@@Rigel_Chiokiswrong axle and tire ratings are higher then the dot allows for example the drive axles on a semi are legal for 34k but they are rated for 40k by manufacturers. So lift axles are solely there to make sure the truck stays dot legal on weight. The weight ratings are set by the government as the max allowed weight per axle and tire as to provide best service life of roads
@@moparjr89 my country doesn't have a DOT and our rules are different. :)
Stumbled across this video & it's been a question I've always wondered my whole life. Ty for the explanation
I saw a truck on my way to College today with its axle raised up, and it intrigued me. I didn’t even search for this video and somehow my KZhead algorithm recommended this to me coincidentally 😅
As a kid I always thought these were just spare tires lol
Up until now. I did too.. I'm 40. 😂 makes more sense that it was a lift able axle now though. You'd need some serious tools to change one of those tires.
LOL, I always thought it was the spare tires!
I love semi-trailer trucks and your vids, thanx for your content! I wonder considering the 6x2 config which is better. Is it better to have the steerable lift axle after the driven axle or before it? Hope you will once cover the topic of steerable semitrailers. That would be cool. Keep on the nice work, good luck to you!
This was one of the most interesting and informative videos I've ever seen on KZhead. On the high side of 60, I've wondered about this for decades. Thank you.
Thank you 👍
If you have a lift axle on a truck tractor and go to Alberta, you cannot use it and it must be "Chained up". Now in South Dakota a lift axle on a truck or truck tractor must have a "lift axle permit" The control of the lift axle usually must be outside the cab so it cannot be changed while driving.
Just shows that Alberta has mental people making rules. In BC you just raise them and that's all that's needed. Chains, WTF.
It's 3 AM, wtf am I doing here
Same 😂😂
Actually it's 4 am now🙂↕️
Same for me lol
I always wondered about those, and had an idea of what they were for, but this video explained it in detail in a language anyone could understand.
I'm super impressed that you were able to make a 6:30 long video where you talked the entire time, yet never actually said anything. That's not easy to do!
I assumed it was save tire wear (seened an expensive way to "save" money.) Also for tolls if they only charge for axles touching the road. My issue is id say 97% of lift axles i see are lifted all the time. Im wondering does the average driver really calculate axle weight & raise & lower it as needed? Or is it lifted on day one & never actually put in use?
It's every truckers responsibility to know you're within weight regulations. Either by knowing the weight of your cargo or drive onto a weight station, and then lower the tag axle if needed. The money you save by trying to cheat the system is not enough to cover even a fraction of the fine you risk if you get busted with overweight.
@@DonGorgen i agree, but I'm really talking about the dump trucks making local runs where they're not gonna be stopped for weighing or anything else (at least not where I live). I rarely if ever see the lift wheels down. I don't think local drivers really care to bother with calculations & all that.
That may be because you are only noticing the ones that are up in the air and not rolling. When that axle is lowered we all tend not to even notice it.
From my experience in Snowrunner, Keeping the axle lifted helps with traction more for some reason, even though it should be the opposite
Less wheels carrying the weight => more weight on each wheel. More weight => more traction. Hope it helps
The lowered non driven axle also prevents the driven axles from digging into lose ground where the tyres can reach some traction, because it's just sitting on top
The issue is though, it doesn't seem to be that effective in Snowrunner Occasionally it's helpful, but usually I can go through mud faster if the wheels are raised It's the opposite to what I'd expect
@@owlenderg Sounds like what you're describing isn't traction, but reduced friction. Assuming you don't need the extra pulling power having fewer wheels on the ground will mean less friction to push against.
I always raise my tractor tag when it snows. It drops my steer down to 10k when I'm loaded and tag down. I can get 3 to 4 k more on my steers by raising my tag. Really helpful for turning in slick conditions
Playing truck simulators helps me learn a bit of the basics of trucking
This is a question I asked myself when I was a kid but no one could answer me and I had no internet. Almost 20 years later I find the answer!
I always thought it was because the tires get tired, so they take it in shifts.
Lift axles in front of driven axles are pushers. In the video they were referred to as just lift axles. There is another version not mentioned too, the steerable pusher, usually added as a second pusher. A more concise reason for lift axles is to allow trucks to stay under the maximum weight per axle limit on some roads or bridges.
Your more concise reason for lift axles is simply not a reason for lift axles. In fact, this is the problem I had with this video as well. Most of what was told has nothing to do with the lift itself. No, lift axles are NOT there to distribute the weight across more axles or to deal with weight regulations. That is what an extra AXLE is for. If it was permanently lowered type, there would be literally zero difference for any of these purposes. The lift part is there strictly to save money on things like fuel and wear when the extra axles are NOT needed. Nothing more and nothing else. Remember, a non-lift axle is the default! Therefore reasons for a 'lift axle' is reasons to add a lift mechanism to a non-lift axle, and NOT a reason to add additional axle!
@kikixchannel Lift axles take weight off the driven axles to meet the local and state road axle limits. Most states only allow 34k lbs on tandem axles. You can haul more by putting a lift axle down. Lift axles are rated by the weight they lift. Tags are usually 13.5k lbs and pushers are 12-20k lbs. Truck designers add lift axles to keep all axles when loaded under the axle weight limits for areas they are traveling.
@@jmaus2k You do not understand the point of my post... I know that putting the lift axle spreads the weight between larger surface and more axles. However, this is not a trait of the LIFT axle, but of an AXLE altogether. If you have eight axles and two are lift axles, when they are down, the distribution is exactly the same as when you have four axles and none are lift axles. Therefore, the 'lift' function in the axle has literally zero effect on the adherence to the regulations. The lift is NOT added for adherence to legal limits. It is added so that you can save on running costs by not having to go for full load capacity at all times. Basically, you are putting the cart before the horse. Again, a standard axle is the default, the lift is an add-on. Don't make the lift the default when it's not.
@@kikixchannel You can't easily add solid axles that are down all the time in front of tandems. In fact there are no solid axle options for the center frame mounting of trucks because the driveline is in the way. To avoid scrubbing tires when turning you also can lift up lift axles. So it is the most reasonable way to add weight capacity to a truck. And of course, they can be lifted when empty to save fuel. They can also be lifted where roads are less strict. Primarily the reason to buy a lift axle option on a truck is to gain weight capacity(after you get past tandem axles).
You can also shrink your turning radius a little by picking up an axle. Not by much, but every little bit helps.
Civil engineer here. More axles doesn't mean less wear and tear of road. Quite opposite, if they are put in a row with little gap between them, 2 axles will destroy road less than 3. It's because for asphalt more damaging in this case is sudden compression and decompression cycles one after another than weight itself. That is why regulations (at least here in Europe) specify max single axel load depending on distance between wheels, from 11t at less than 1m up to 20t above 1,8m.
What's the purpose of the music? To distract? To annoy?
To entertain?
@@TruckTropia Nope, didn't work.
Tracey have a great Christmas 😊😊😊❤😮😊
I had the dumbest idea - thought they were spare Tyres. 👍🏿Informative
In the 70s i drove a Volvo F86 with a raised axel configuration. Great for farm deliveries in Scotland in winter.
Don't forget axel rose
It should read Why Doesn't it touch the ground?
Thanks for sharing, always wondered about this when I see wheels lifted on a truck
This feels like I'm watching that news report about: "10 people died in a fire in the Bronx last night".
I alaway thought they are spares
They can be if you run steer tires on them
Thank you for your explanation and being straight to the point.
I never knew this I had speculations but never really knew... Thanks !
THANK YOU ! Since I was a kid my lifelong question is now answered
No problem 👍
Take a drink every time he says "distribute the load evenly."
Thank you for making this video. I always thought the tires were just spares in case of a blowout.
I learn about this playing Snow Runner .. 😂😂😂 Some of the Trucks have these type of Axles in the game and after a while, you kind of get a sense of what role they play when you use them in different scenarios ..
I drove Heavy Trash Trucks in National Parks for 25 years WAY UP in the Mountains.. Front Loaders and Rolloffs. Tag axles are great. Two added tons of payload. When you’re 60 miles from a landfill that comes in handy. The added braking really helped too.
What a great “office” location. You were a lucky guy.
5:42 I had to play it twice to be sure, but he really does say "so, to answer the title of the video's question".
In european trucks, we have had "automatic" axles for years now, when a sensor measures enough weight on one axle, it will drop down lift axles to balance them out. Also nowadays they have automatic balancing feature too so the liftable axle isn't pushing down with full force but instead just enough so that the drive axle is at full legal maximum load.
Sometimes we forget just how beautiful machinery is.
As a CDL driver. Who’s done gravel trucks and trailer trucks for 10 years. It’s for weight. You move it down for frame support if the load is too heavy.
Thank you for the wonderful explanations regarding these wheels.
That's some neat info, always assumed they were for emergencies if a tyre blows.
It's 2:30 in the morning and I'm watching this, not complainin' though, nice video
The lift axel automaticly lowers itself when the load reaches a fixed amount of weight. You cant choose to lift it fully loaded
I remember one time in Sweden, I drove a 3-axle Scania with 3-axle trailer and I didn't have a load on, so I had the truck's last and trailer's first axle lifted, when I drove to a gas station, where was a bus with Japanese tourists. And it was so funny for most of them, when passed them- they pointed finger at my lifted axles and laughed, probably it was funny for them, because they couldn't probably understand, why would one need so many wheels, when I don't use them :D
What’s weird is I’ve been wondering about this for a few weeks. I didn’t do a search for this, but your video popped up. Is KZhead/Google reading my mind?
there is also the issue of road tolls. some roads charge trucks PER AXLE, like the Verrazzano bridge in NYC. having less axles on the ground when not in use can save thousands of dollars a year in tolls.
not sure how this channel got into my algorithm but interesting stuff, i've seen this before and wondered but never fully looked into it. now i know so that's pretty awesome
Welcome to you 👍
Im in the states. I've only seen them on cement trucks. Thought they were used to not high center. Great video.
i’ve been wondering this since i was a kid, crazy seeing this now lol
Yea it’s happening. I was thinking about this a couple days ago I’m my head. I wasn’t even looking at a truck. Just popped in my head. Yt algorithm is reading minds now
Love watching trucks. Like to see them on the different roads. Can’t beat a truck for heavy loads.
Really? What's use to deliver trucks to market? I'm thinking ships and rail.
I thought "lift-axles" was "stationary axles" that was built to be a bit higher up, but low enough that when a heavy load was placed on the truck, it would push it all down so the "stationary axle" would come into contact with the ground & therefore take up some of the weight, I didn't expect them to be movable, even if that makes more sense, but creates more parts that can break.
Several of those reasons are obvious to me, but, some others I never though of. Interesting and educational. Thank you.
Welcome 👍
I have a lift axle on my truck solely for heavy loads. It's a 4 axle truck, and the first axle in the drive group (closest to the cab) can be lowered to meet the bridge law requirements. The pressure in the airbags can be adjusted to shift weight between the steer axle and the drive axle group. Adding another full axle allows an additional 20,000 pounds to be permitted on the drive group, up to 60k on 3 axles (in most places). I also run a RGN trailer with 3 fixed axles and a pin-on flip. 4 pins hold the last axle onto the trailer. 2 pins can be removed and the axle can be flipped up when not needed. Or all 4 pins can be removed and the axle comes off.